Although it's recommended you take your motorcycle to a professional with the correct diagnostic tools, you can read the DTC / fault codes on the DN-01 with the "paperclip trick".
Remove the passenger seat by inserting the key into the side key slot located underneath your LEFT BUTT CHEEK (fnarr) as you sit on the bike (and it would be recommended you remove the drivers seat, this is held in by 2x 10 mm bolts), you will then see a small red plug just behind the fuel tank.
With the ignition off, remove the red plastic cover and gently insert a paperclip (or a small piece of wire) between the pins for the GREEN (with yellow stripe) and BROWN wires - be careful as there's another BROWN wire with a stripe, make sure to use the BROWN only wire.
When the Green/yellow and Brown wires are shorted, you have 2 choices;
Either just turn the ignition on to read only the PGM-FI (engine) fault codes (read from the MIL light)
Or hold down the D / Gear + button whilst turning on the ignition to read only the HFT (gearbox) fault codes (read from the gear indicator flashing a horizontal - line)
Codes are flashed out with blocks of ten in long (1~ second) flashes and blocks of 1 in short (under half a second) flashes, for example two long flashes followed by six short flashes would be a fault code of 26.
Once you have finished reading the fault codes, turn the ignition off, remove the paperclip / wire, then re-assemble everything.